mozaic trigger system for transverse momentum physics
DESCRIPTION
Mozaic trigger system for transverse momentum physics. G.Vesztergombi , A.Agocs, B.Bozsogi, A.Fulop CBM Collaboration Meeting GSI – Dubna 13-18 Oct , 200 8. Motivation for new measurements below = 20 GeV. - PowerPoint PPT PresentationTRANSCRIPT
Mozaic trigger system for transverse momentum physics
G.Vesztergombi, A.Agocs, B.Bozsogi, A.Fulop
CBM Collaboration Meeting
GSI – Dubna13-18 Oct, 2008
Motivation for new measurements below = 20 GeVs
Practically no high or medium Pt data between Einc = 24 and 200 GeV
Mysterious transition around 80-90 GeV: convex versus concave spectra
Energy threshold for Jet-quenching?
Emergence of Cronin-effect in pA interactions is completely unknown
energy dependencecentrality dependenceparticle type dependenceparticle correlations
Production of Upsilon (9.5 GeV) particles near the threshold.
NA49 (CERN) results at 158FODS (IHEP) at 70 GeV
Beier (1978)
Y production
Due to high mass ( 9.5 GeV/c2) two high pT particle in leptonic decay:
pT > 3 GeV/c
High selectivity for high pT pair even without PID
Benchmark NA49 pp at E = 158 GeV 30 events/spill Events Energy > 3 GeV/c > 4 GeV/c > 5 GeV/c
2 106 158 100 1 0.01Estimates with the assumption 1011 proton/sec 109 interaction/sec
1 day=1014 158 5 109 5 107 5 105
Suppression 10-1 10-2 10-3
1 day=1014 90 5 108 5 105 500
20 day=2 1015 90 1010 107 104
20 day=2 1015 45 107 10 0
Suppression 10-3 10-6 10-10
For symmetric nuclei max energy 90/2 assumed
CBM Perspectives
Special requirements for Y-> e+e- and high pT
Extremely high intensity - Pile-up
Segmented multi-target - Relaxed vertex precision
Straight tracks - High momentum tracks
DREAM: 109 interactions/sec
High transverse momentum means high 3-momentum
Illustration for mid-rapidity at sqrt(s) 7 and 14 GeV
( )ELab
( )( ) =plong
ptrans 0 0 1
0
0
22Tpm
0
longp >= 0Lab
E >= 22Tpm
ptrans
Beam ptrans Lab
E
25 55525 2 5
5 22
z [cm]
x,y
[cm
]
Px=Py = 1 GeV/c; Pz= 5 GeV/c
Px=Py= 3 GeV/c Pz = 10 GeV/c
High ( > 5 GeV/c ) momentum Straight track
“Straight” tracks from main vertex
1-dim Hough – transform:- histogram
N(i) in bins
M(i) = N(i) + N(i+1 ) in 2bins
Correct for bin boundary crossing:
Tracks with pxz > pmin remains within the pminwedge
SELECTION on pxz
i
i+1
j
j+1
3 dimensional scheme
k=1
k=2
k=3
Mosaic cells in plane “k” : M(i,j,k)
(i,j) Corridor contains: M(i,j,k), M(i,j+1,k), M(i+1,j,k), M(i+1,j+1,k) k=1,2,3
MAPS vs Hybrid
Vertex resolution: dz = 1 mm, dx,dy= 0.05 mm
High intensity: radiation hard
Practical 4+ 2 + 3 = 9 planes ( 4 Hybrids + 5 strips)
Selectivity depends on the availability of TOF information
s = sqrt(XX*XX+YY*YY) - delta
delta
Sagitta:
10-20 cm track sections are practically straight fractals
(XX,YY,ZZ)
4 hybrids 2 + 3 strips
2 4 6Basic planes
* * **
** **
*
Silicon planes
Basic planes: #2 = (x2,y2,z2) pixel , #4 = (x4,y4,z4) pixel, #6 = (x6,z6) strip
Parallel processing: CORRIDOR # corNum
Straight tracking in #2 and #4 planes in space => (mx,bx) and (my,by) Approximation: starting direction is given by (mx,my)
Separate track matching in xand y for planes 5-9
Matching in #1 and #3 pixel planes in space
TUBE definition:
x-tube: xi = mx*(zi-z2) +bx +parabol(x6,z6,zi) +/- deltaxiy-tube: yi = my*(zi-z2) +by +/- deltayi
New algorithm
4-5 GeV/c
pT > 1.0
7-8 GeV/c
pT > 1.0
9-10 GeV/c
pT > 1.0
15-17 GeV/c
pT > 2.5
20-40 GeV/c
pT > 2.5
Acceptance
Npoint=9
+ -
pxz
pT
Selecting only tracks with pT>2.5 GeV/c
Npoint=9
PileupFixed pT-cut at 1.8GeV/c
No pileup : Tracks with ptin > 1.8: 1136 ptin < 1.8 but ptrec > 1.8: 430
Npileup = 10 : Tracks with ptin > 1.8: 1136 FAKE and ptrec error : 1 + 430
Npileup = 100 : Tracks with ptin > 1.8: 1136 FAKE and ptrec error : 28 + 430
Npileup = 1000 : Tracks with ptin > 1.8: 1136 FAKE and ptrec error : 464 + 430
No LOSS of GOOD tracks due to pileup (exhaustive search!!!)
Number of FAKE triggers even in 1000-fold pileup is < 50 %
Pileup cont.
pT dependence: No pileup 1000-fold pileup
1.8 GeV/c 430/1136 464+430/1136
2.0 GeV/c 312/704 363+312/704
2.2 GeV/c 208/453 306+208/453
2.4 GeV/c 151/301 265+151/301
2.6 GeV/c 103/213 205+103/213
3.0 GeV/c 52/154 168+ 52/154
The FAKE/GOOD ratio is moderately increasing with pT
Deviations within the tubedx Charge*dx
Y-deviations
Difference between exact direction and mx
pT > 1.0 GeV/c pT > 2.5 GeV/cpxz
DAQ scheme
Mozaic DAQ systemTwo separate systems:
PRETRACKING network: Pixel [#2 , #4] + Strip [#6x]
TRACK-QUALITY TUBE network:Pixel [ #1, #3] + Strip[#5x, #5y, #6y, #7x, #7y, #8x, #8y, #9x, #9y]
In each network parallel CORRIDOR processors: CorID =corNUMNumber of CORRIDOR processors: ndx*ndy
Data select their routes according to plane number and corNUM
In plane „zi” track-hit „xi,yi” calculates its corridor address:
corNum = idx*ndy + idy
Corridor processors
OLD system: consecutive cycling on all „planes”
If only 2 points per plane: number of cycles = 2(4+2*5) = 214 = 16384
NEW system: cycling only on 3 „planes” (for pixels x and y has common cycle)
If only 2 points per plane: number of cycles = 2(2+1) = 23 = 8
The PRETRACKING is producing a list containing:
corNUM, x1,x3,x5,x7,x8,x9, y1,y3,y5,y6,y7,y8,y9
There is NO PROCESSING TIME in the TRACK-QUALITY TUBE network becauseIt is only an ASSOCIATIVE memory which provides YES/NO.
The gain in processing time (if only 2 points per plane): 211 = 2048-fold
Mozaic trigger for low pT
Silicon tracker in FAIR-CBM experiment
Special trigger for high intensity 1O9 interaction/sec in pp,pA reactions
SIMULATION: 4 hybrid(pixel) + 5 strip = 9 silicon planes
“Mosaic” front-end structure (dx,dy) regions in M(i,j,k) buffers.
Exhaustive search for all tracks in (pmin,pmax) corridors.
TEST RESULT: 1000-fold PILEUP in pC interactions
Corridor-width optimized for tracks pT > 3 GeV/c
Algorithm efficiency: 100 %, with some multiple solutions picking up some random points, giving practically the same track-parameters
Highly parallel algorithm is well adapted for processor clusters.
Can be adapted for AA to reconstruct ALL particles with low pT corridors
END
For discussion:
Physical mosaic cells can be different from logical cells.
Hybrid (pixel) : logical cells may be created by softwareStrip planes: hardware should be harmonized
Corridors can be filled by hardware or software
Number of processor can be less than number of corridors
Corridor’s processing speed can be very fast if they are narrow
Corridors can be arranged hierarchically for processing order
0 0 0 1 0 0 0 0 1 0 0 1 0 0 1 0 0 2 0 00 3 22 5 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 04 0 48 73 44 7 1 0 0 0 1 1 0 0 0 0 1 0 0 00 0 34 81 90 81 35 0 0 0 0 0 0 0 1 0 1 0 0 00 2 28 83 92 87 89 81 25 0 1 0 2 0 1 0 0 0 1 00 0 17 69 93 89 91 86 87 78 16 1 1 0 0 1 0 0 0 00 0 4 40 86 90 90 85 91 87 86 63 13 1 0 1 0 0 1 10 1 1 18 72 94 91 90 89 85 87 87 83 42 9 0 1 0 1 00 0 0 9 52 88 90 88 85 86 93 93 91 89 77 50 8 0 0 30 0 1 0 28 72 88 90 90 91 85 90 86 91 90 84 80 37 0 00 0 0 0 8 51 74 92 92 87 91 86 91 95 90 83 93 88 75 260 0 0 1 1 37 62 89 87 87 88 84 85 92 96 92 91 90 90 89
Plong [GeV/c]
Ptrans [G
eV/c]
10 20 30 40 50
7+2 Points efficiency
2
0
4
6